Recently, high quality digital video and high quality digital audio are provided through DVDs, digital TV sets, and the like. Digital video data and digital audio increase in data amount as the qualities thereof are increased, and therefore, such data is compressed once for storage and transmission thereof in general. An encoding system (hereinafter referred to as an encoder) performs compression of digital data while a decoding system (hereinafter referred to as a decoder) performs expansion thereof, wherein these systems are composed of dedicated semiconductor elements usually.
Novel digital compression techniques for increasing the quality of video or audio are devised and reduced to practice day after day. In order to reduce to practice such novel digital compression techniques, the encoder and the decoder must cope with the novel techniques.
The decoder and the encoder for digital video or digital audio are required to be developed within a extremely short period of time in many cases. While, modification of hardware of semiconductors needs rather long time compared with modification of software. Therefore, a DSP (Digital Signal Processor) is usually used as the decoder and the encoder so that novel compression/expansion techniques are provided through software. The software implemented in the DSP includes two kinds of digital bit rows of program data that the DSP executes and parameter data that the program data uses.
FIG. 1 is a block diagram showing a configuration of a conventional digital video or audio encoding/decoding device.
A DSP 100 reads out program data 110 from a nonvolatile memory 101 and stores it to a program memory 102 inside the DSP 100. Also, it reads out parameter data 111 from the nonvolatile memory 101 and stores it to a data memory 103 inside the DSP 100.
Thereafter, when the DSP 100 serves as a decoder, the DSP 100 reads compressed digital data 112 into the data memory 103, decodes it, and then, outputs expanded digital data 113 to the outside. On the other hand, when the DSP 100 serves as an encoder, the DSP 100 reads the expanded digital data 113 into the data memory 103, encodes it, and then, outputs compressed digital data 112 to the outside (see Japanese Patent Application Laid Open Publication No. 5-110448A).